Photography consultant and specialist Tim Goldsmith said: "We would of course like to say that the cameras were used by the KGB. But there's no way of proving that. What we can say is that an extra lot of jacket buttons included an original issuing slip from the KGB.

"This is so that the person they were issued to could change all the buttons on their existing jacket to match the button with the camera in, so as to be more discreet."